help无法下载数据且看不出错误的蒟蒻

#include <bits/stdc++.h>
using namespace std;
void dfs(multimap<int,int> &G, vector<bool> &vis, int x, int n)//1->2->5->6->3->7->8->4
{
	cout<<x<<" "; vis[x]=true;
	multimap<int,int>::iterator it=G.find(x);//1-》2
	for(; it!=G.end() && it->first==x; it++)
	{
		int y=it->second;
		if(vis[y]==false)
			dfs(G, vis, y, n);
	}	
	return;
}
void bfs(multimap<int,int> &G, vector<bool> &vis)
{
	queue<int> Q;
	Q.push(1); vis[1]=true;
	while(!Q.empty())
	{
		int x=Q.front(); Q.pop(); cout<<x<<" ";
		multimap<int,int>::iterator it=G.find(x);
		for(; it!=G.end() && it->first==x; it++)
		{
			int y=it->second;
			if(vis[y]==false)
				Q.push(y),vis[y]=true;		
		}
	}
	cout<<endl;
}
int main()
{
	//multimap有向边
	multimap<int,int> G;
	int vn, en;  cin>>vn>>en;
	for(int i=0; i<en; i++)
	{
		int sv, ev; cin>>sv>>ev;
		G.insert(pair<int, int>(sv, ev));
	}
	//multimap+vis动态数组-》dfs输出
	vector<bool> vis(vn+1, false);//1 2 3 ……vn
	dfs(G, vis, 1, vn);
	cout<<endl;
	//multimap+queue-》bfs输出
	for(int i=1; i<=vn; i++)
		vis[i]=false;
	bfs(G, vis);
	return 0;
}
//multimap
//insert find erase
//priority_queue
//push front pop